Two treatment options exist for infant patients with hydrocephalus. Most patients are treated with a surgical procedure in which a shunt is inserted into the brain and abdomen. In recent years, however, another treatment has developed called Endoscopic Third Ventriculostomy (ETV) with Choroid Plexus Cauterization (ETV/CPC).This research study is being done to measure the results of these procedures in children less than six months of age who have hydrocephalus as the result of a brain infection, called post-infectious hydrocephalus, or PIH. This study will evaluate patients in more detail to measure brain growth and development.